Improvement in dies for forming- threads on bolts



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@initrd toiles' Leners Patent `ara-92,567', daad ,my 13, 1869.

IMPROVEMENT IN FOR PO-R-MING-HTHREADS ON BOLTS.

The Schedule referred to in these Letters Patent, and making paxt of the name.

To all whom it may-camera;

Be it known that I, ALEXIS-Banniere, of the city of St. l?etersburg, in the Empire of Russia, have invented certain new and useful Improvements -inthe Mode of and Apparatus for Forming Screw-Threads on Wrought-Iron Bolts; and I do hereby declare 'that the following is a full and exact description thereof, reference being had to the gures of the accompanying drawing, making part of this specification; that is to say- My invention consists in the application, as hereafter described, of a s'waging-process, by means of improved apparatus, to the'formation of screw-threads on wrought-iron bolts.

Figure l, ofthe accompanying drawing, represents in elevation, one of the forms of apparatus by whichl the invention may be executed.

Figure 2 is a sectional plan of the same, through @the line fg, fig. 1.

a is a cast or wrought-inni. fiame,provided with guides a' a', for the vertical motion of the upper swage or die o, which may be raised or lowered by the hand, by the end e.

b c are the steel dies or swages, one of-which, b, is set at the bottom of the frame a, while the other, c, is

adjusted to move vertically between the guides a' a.

The hole h is pierced, through the centre ofthe division-line f g, to a diameter slightly superior to that ofthe bolt to be threaded, and isafterw'ards tapped to the required depth. Thus, for instance, for a bolt of three-quarters ot' au inch,l the hole should have a diameter of about fifteen-sixteenths of an inch. For a one-inch bolt, the .hole should beof one and threeeighths'of an inch, and so on in proportion, or approximately, for the dierent dimensions.

T he'hole being tapped as above, the surfaces of contact of the 'swages vb c are filed, or otherwise ground do\vn,'.until a sharp and deep' thread is bbtained on a test bolt. The vertical plane formed by a cross-section ofthe hole at right angles to itsaxis, is thus reduced to the oval form shown in g. 1, by aid of which ,the cireularity of the bolt is preserved during the threading-process'. l

The bolt ll, g. 2, being brought to a red heat, is passed into the hole .h between the swages b c the hammer is applied to the head of the latter, c, and at same time, the bolt being turned to the extent of a quarter of a circle at each motion, a clear and sharplydeued thread is produced.

The form, dimensions, and general details of -oonstmction 'of the apparatus, may of ourse be varied ac- Y cording'tocircumstances. I

Having now described the nature of my said inveul tionfaud the manner in which it may becarred into effect I declare' thatwhat I claim, aud desire to protect by Letters Patent, is

Forming the threading-dies b c of an oval shape in cross-section, substantially as shown and described, and for the purpose set forth,

A. BELAIEFF. Witnesses:

N. TELESCHEFF, A.- ALBINSKY. 

